The invention relates to a method of and to an apparatus for treating uncured tobacco leaves (also called green tobacco). More particularly, the invention relates to improvements in methods of and in apparatus for treating uncured tobacco leaves for storage and/or shipment.
Harvested tobacco leaves are dried and normally fermented prior to shipment to processing plants. Such leaves have a moisture content of less than 25 percent, normally 12 to 17 percent and in most instances 14 to 16 percent. The leaves are often subjected to a compacting action to form bales or similar accumulations and the bales are delivered to processing plants which prepare them for extended storage and/or shipment--often overseas--to cigarette making factories or other types of factories which make smokers' products.
It is very important to ensure that the moisture content of uncured tobacco leaves match or closely approximate a value which is best suited for storage and shipment. The leaves or parts of leaves, such as ribs and tobacco leaf laminae (hereinafter called strips for short), are normally compacted preparatory to shipment and their moisture content should be in the range of 11 to 13 percent or very close to such value. Excessive moisture content is undesirable and damaging because the leaves and their parts then exhibit the tendency to mildew and they are likely to constitute a fertile ground for the growth of fungi. On the other hand, excessive drying of uncured tobacco leaves and/or their parts can lead to a reduction of quality because the leaves and their parts are brittle and tend to break during conversion into bales or the like.
The presently preferred methods of treating uncured tobacco leaves include subdivision of leaves into ribs and strips. The ribs are thereupon separated from strips and are treated separately. As a rule, such treatment involves introduction of ribs into suitable containers which are then prepared for storage or shipment. The separated strips are condensed or compacted to form bales or similar accumulations (hereinafter called bales for short) which are introduced into packing machines and are made ready for storage and/or shipment.
Condensing of strips or whole uncured leaves normally takes place at room temperature and at a moisture content of 10-11 percent which is the desired moisture content for storage and shipment. Such moisture content is too low for conensing into bales because a large percentage of leaves and strips breaks and suffers a pronounced loss of quality because the material which is converted into the fillers of cigarettes does not contain a high percentage of long shreds.